> ## Documentation Index
> Fetch the complete documentation index at: https://docs.doblier.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Upgrade & Rollback

> Versioned upgrades with a rehearsed way back.

Upgrades follow the [versioning policy](/platform/release/versioning-policy): PATCH releases are drop-in; MINOR releases are rolling with no event loss; MAJOR releases ship a migration guide and are rehearsed in shadow before production.

Every upgrade is preceded by a mandatory checkpoint set — Flink savepoints, schema-compatibility verification, ClickHouse backup — so rollback is a rehearsed procedure, not an improvisation. Recovery behavior is re-verified against the [chaos suite](/orca/operations/chaos-testing) at every MAJOR upgrade.

Detailed per-version upgrade instructions ship with each release package and in the customer portal.

<Snippet file="cta-architect.mdx" />